This invention relates to an endoscope having a high-frequency incising and excising instrument by which polyps, tumors, growths, or the like, in and along internal passages of a human or animal body and accessible through a body opening can be incised and removed by passing a high-frequency current through a wire loop.
Endoscopes, in recent years, have become and continue to be more widely and extensively used in medical and industrial fields where areas not otherwise exposed or accessible can be viewed and procedures performed thereon. Two basic types of endoscopes are used, one having a hard or rigid distal end for insertion into the area to be viewed or where a procedure is to be performed and the other having a soft or flexible distal end. Where the distal end is soft or flexible, the soft or flexible end can be bent or deflected as it is inserted into the opening and passed throught the passage. In both instances, the endoscopes are designed so that the desired area or areas along the internal passage can be observed and dignosis made at the distal end from the remote or proximal end of the endoscope and so that, where required, treatment can be effected to the area at the distal end by means of instruments inserted through a channel in the endoscope and manipulated from the proximal end.
One medical procedure in which endoscopes, as described above, are commonly used is in the location, diagnosis and removal of phyma or polyps from the walls of the stomach. The stomach wall is examined from the distal end of the endoscope, the phyma or polyps are located and diagnosed and can then be excised by a high frequency incising and excising instrument inserted through the channel of a treatment instrument while being observed through the endoscope.
In Japanese Utility Model Publication No. 50377/76 there is disclosed an example of an incising and excising instrument having, as shown in FIG. 1(a) hereof, a ring 2 inside of a sheath at the distal end of a flexible tube 1. A freely advancing and retracting slider 3 is positioned inside of flexible tube 1, behind ring 2, and is fixed to the bent end portion 4 of wire loop 5. The opposite end of wire loop 5 extends through passage 6 in slider 3 and axially through tube to the proximal end, not shown, where the wire is fastened to a handle, loop, or other device by which the wire and wire loop 5 can be manipulated. By manipulating wire loop 5 from the opposite, or proximal end of flexible tube 1, loop 5 can be advanced from the sheath end of tube 1, the bent portion 4 of wire loop 5 can be hooked around the polyp to be incised and tightened, in the body cavity, around such polyp. By applying high frequency current to the wire loop, the polyp is burnt out. However, after the exercising of several polyps in this manner, carbides form on the wire loop, stick to the wire and the loop is deformed. As a result, high mechanical resistance to the advance and retraction of wire loop 5 through passage 6 in slider 3 is encountered. Thus, slider 3 is pulled toward the proximal or handle end of tube 1 before loop 5 is completely closed, resulting in the loop remaining open as shown in FIG. 1(b). When loop 5 is drawn further toward the proximal or handle end of tube 1 in an attempt to close the loop, the length of the loop, from the bent end portion 4 changes. As a result, a small loop is formed in a vertical direction to the longitudinal axis of the flexible tube 1, as shown in FIG. 1(c). The loop, even if further pulled, can not be closed. Thus, the instrument becomes useless. Under the worst conditions, the loop is frozen and can not be reopened. To overcome this problem, an annular stopper 5A, as shown in FIG. 1(a), is adhered to wire loop 5. When stopper 5A contacts slider 3, the slider is drawn into tube 1 and the bent portion 4 of wire loop 5 is drawn into the distal end of tube 1 after wire loop 5 is closed and exercising is completed.
In Japanese Laid-Open Utility Model Application No. 104506/81 and as shown in FIG. 2 hereof, there is an improvement in the instrument of the afore described Utility Model Publication. In such improvement, a flexible C ring 7, FIG. 2(a), is mounted inside flexible sheath 1, a part of the sheath 1, as shown in FIG. 2(b), is formed to project inwardly as a convex portion, or, as shown in FIG. 2(c), a convex portion 10 is formed on lever 9 by extending the rear end side of the engagement ring 2. Where slider 5A, FIG. 1, is pushed forward through C ring 7, however, the C ring is pushed forward before slider 3 goes through C ring 7. This, of course, is not desirable. As to the convex portion 8 in FIG. 2(b), such convex portion tends to become flattened by the repeated movement of slider 3 through the convex portion. This, of course, is also not desirable. In the arrangement of FIG. 2(c), the engagement ring 2 forming the convex portion 10, when it contacts the inside of tube closely, prevents slider 3 from being pushed in and the flexibility of lever 9 of engagement ring 2 is lost. This, also, is not desirable.